1. Field of the Invention
The present invention is directed generally to an energy and data transmission system operating without contact and being composed of a microstation and a microunit.
2. Description of the Related Art
Data carriers and data equipment in the form of, for example, chip cards having integrated electronic components, are utilized in a great variety of applications. In almost all such systems that are commercially available, contacts are provided between the card and the reader means. Such contacts are disadvantageous since they are subject to contamination, static discharges, vibrations and wear.
These disadvantages do not occur in a contact-free system that operates inductively.
When energy and data signals are transmitted in a non-contacting fashion, it is obvious to employ a transmission frequency that the microunit can use as a clock signal for operating electronic circuit assemblies in the microunit, the clock signals being either identical to the transmission frequency or directly acquired therefrom by subdividing. Moreover, the frequency employed should satisfy international guidelines or potential standards. The frequency employed thus must be held constant. Due, however, to aging and to component tolerances, the component parts that are used in the resonant circuit for generating the transmission oscillation frequency are altered so that the natural frequency of the resonant circuit no longer agrees with the control frequency when component part parameters are altered in such fashion. As a result, the energy transmission between the microstation and the microunit is diminished. A further condition is that two resonant circuits must have a constant phase relation relative to one another for unambiguous signal recognition by the microunit. The foregoing problem is essentially combined in the demand.